Guinea Pig Pregnancy Calculator

Enter the breeding date to estimate your guinea pig's due date, based on the average 68-day gestation and the normal 59–72 day range.

Quick Facts

Method
Due date = breeding date + 68 days
Normal range is 59–72 days; large litters often arrive earlier.

Your Results

Calculated
Most likely due date
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Breeding date + gestation length
Earliest expected
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Breeding date + 59 days
Latest expected
-
Breeding date + 72 days
Days remaining
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From today to the due date

Ready

Enter the breeding date and calculate the due date.

How the guinea pig pregnancy calculator works

Guinea pigs (Cavia porcellus) have one of the longest gestation periods of any small rodent. The average pregnancy lasts about 68 days, with a normal range of roughly 59 to 72 days. This calculator takes the date the sow was bred (mated) and adds the gestation length to estimate when she is likely to give birth, along with the earliest and latest dates you should be watching for the litter.

The core formula is simply:

Due date = breeding date + 68 days

Because delivery is a range rather than a single guaranteed day, the tool also reports the earliest expected date (breeding date + 59 days) and the latest expected date (breeding date + 72 days). You can adjust the gestation-length field if your vet or breeding records suggest a different figure for your line of animals.

Why the length varies

Litter size is the biggest factor. Larger litters (four to six pups) tend to be delivered a little earlier, often around 59–63 days, while smaller litters of one or two pups may go the full 68–72 days because the fewer, larger pups take longer to mature. First-time mothers and the individual sow's genetics also shift the exact day within the normal window.

Key guinea pig pregnancy facts

  • Average gestation: ~68 days (about 9.5 weeks).
  • Normal range: 59–72 days.
  • Typical litter size: 2–4 pups (range 1–6).
  • Pups are precocial: born fully furred, eyes open, and able to walk and nibble solid food within hours.
  • Sow can conceive again immediately: a fertile postpartum estrus occurs within hours of giving birth, so separate the boar to avoid back-to-back pregnancies.

Reference points you can check the estimate against

A pregnancy that began on 1 March gives a most-likely due date of 8 May (68 days later), an earliest date of 29 April (59 days), and a latest date of 12 May (72 days). If you only remember the week of breeding, use the first day of that week for a conservative early estimate and the last day for the latest date.

Frequently Asked Questions

How long are guinea pigs pregnant?
On average about 68 days, with a normal range of 59 to 72 days. Larger litters are often delivered toward the early end of that range and small litters toward the late end.
When can I feel the pups moving?
You can usually feel the pups shifting inside the abdomen from about week 5 (around day 35), and the sow's weight roughly doubles by the end of pregnancy. Handle her gently and support her whole body — never press on the abdomen to "count" pups, as this can injure them.
What should I do as the due date approaches?
Provide a quiet, clean cage with unlimited timothy hay, fresh water, and vitamin-C-rich food. Guinea pigs give birth quickly and rarely need help, but watch for a sow who strains for more than 15–20 minutes without producing a pup, or who is still pregnant past day 72 — both warrant an urgent call to an exotics-experienced vet, as dystocia (difficult birth) can be life-threatening.
Is this calculator a substitute for veterinary care?
No. It estimates a due-date window from the breeding date only; it cannot confirm pregnancy or assess the health of the sow or pups. Guinea pig pregnancy carries real risks such as pregnancy toxemia, so a bred sow should be seen by a vet for confirmation and monitoring.

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